Add time zones to database (and support in app) #43
Description
To keep things simple, and because we were only supporting one event at a time, our initial data model used timezone-less dates (and timestamps) for events, festivals, etc. This has already caused the occasional edge-case problem, but more importantly it prevents us from scaling to true multi-festival support. It was chosen tech debt which now has to be paid.
Some considerations:
- Database migration will be delicate. We may need a custom script to perform all the conversions
- We have lots of date/time comparison logic that will need to be updated and tested
- UI will have to become aware of time zones (for example, when creating new events the user will have to pick one)